I have a map configured with maxz=20. `tirex-status` does not display any statistics for zoom larger 17 until some tiles are rendered. Expectation is that a 0 is displayed also for higher zoom levels up to maxz. ``` Statistics: count_error=0 count_expired=0 count_rendered[osm]=0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 4, 478, 3 count_requested=501 count_timeouted=0 sum_render_time[osm]=0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2.111, 0, 0.815, 8.057, 8.050, 37.050, 2:24:20.754, 27.504 ```